The militant heritage group has attacked the proposals - which were drawn up by Allies and Morrison and Dimitri Porphirios for developer Argent - over two historic buildings that it claims should be retained.
In a letter to Camden council, SAVE secretary Adam Wilkinson hit out at the masterplan calling for the Culross Building and Northern Stanley Building not to be demolished.
The vast scheme, which would see a huge retail, residential and office scheme constructed, is currently working its way through planning.
'The proposed demolition of the Northern Stanley Building to make way for a road is wholly unacceptable and redolent of the prevailing attitudes of the 1960s and 1970s where the highways engineers wrought destruction on our towns and cities,' Wilkinson's letter states.
'It remains our position that the demolition of both of these important buildings within the conservation area is in itself unnecessary, and is a by-product of the imposition of a plan on the site that disregards the built heritage in the southern part of the site,' the letter adds.
It remains to be seen if the scheme will win full outline planning from Camden council. It has caused widespread controversy within the planning authority and planning committee.